cocoa: fix interaction of combo-field% popup and canvas refresh   and also reduce work on redundant show/hide of canvas  Closes PR 11557
cocoa: fix interaction of combo-field% popup and canvas refresh
  and also reduce work on redundant show/hide of canvas
 Closes PR 11557

mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket,mafagafogigante/racket